rx400hinLI

Hi All,
Just bought a '07 400h. Love the car thus far. A few questions though.

1.) I know the '06 RX had a recall (or just a recurring problem) between 35-40mph where it would stutter and vibrate. I noticed something similar, however when passing 40mph in my '07. I think it may be normal however, but here goes.
When I pass 40mph (usually accelerating onto a highway or in traffic), and if the dashboard shows both battery and engine power (not sure of the technical terms for it) the car makes a loud revving noise. It doesn't vibrate, however the noise is noticeable. Is this normal (an aspect of CVT or the hybrid system perhaps) or indicative of a larger problem. I am somewhat of a perfectionist so while others may not notice it, I would.
2.) My Bluetooth connection drops constantly. I have a V3 razr and the in-dash system I have is Gen5 with 6.1 software in it. Often in a call the display will say "call terminated by network" but I can continue it on my phone. This often happens when I begin to loose network coverage. However it has happened in other places.
3.) I get wildly varying gas mileage. At first it was 20mpg, now with 90% city driving and often less than 2 mile trips (Boston driving) it drops from 12.8 to 17.3 mpg. I think this is probably normal and is indicitive of my driving style (rev the engine to pass other cars) and plenty of sitting in a car while not moving. Perhaps I should allow the battery to drive the car more?

Lastly I love this car, how are others loving the '07s?

Nextourer

Hello and welcome to Club Lexus!

1) The revving of the engine is normal as the RXh is equipped with a CVT-type transmission (I don't know how technical you want me to go). With a CVT, the transmission will match the engine speed depending on the amount of power you requested, the load on the car and the road terrain (up/down hill, flat). So, unlike a normal car where it would downshift, the RXh will just rev up and off you go! It's just a characteristic of CVTs. This setup means NO shifts and no waiting for the transmission to figure out what to do - just punch it, let it rev and there she goes.

2) I can't answer the bluetooth issue


3) Opposite to what seems logical, using the battery more actually *reduces* mpg. The reason? Unless you intend to go down a big hill afterwards, the battery will be charged by the engine which means using more fuel. There are also "losses" between conversion from fuel to kinetic, then potential stored int the battery, then back to kinetic.

The first 5 mins of any trip will result is appalling mileage as the engine runs to warm up and such. This is one of the reason why they said to combine trips and hopefully the trips are longer than 5 mins in the city.

The power in the RXh is seductive and it's oh-so tempting to dip the accelerator a bit more. The best way to maximise mileage is to anticipate traffic (and lights) and glide. "Glide" refers to the "mode" where the engine is off and there's NO arrows to or from the battery. This is achieved by lightly pressing the accelerator. Neutral gives the same effect but you won't be in gear. "Coasting" is with the engine off and green arrows to the battery (regen) and "stealth" is using the battery to power the vehicle.

An advance technique is "Pulse & Glide" which isn't recommended for use in traffic but otherwise would help maximise mileage if you wish to pursue that route.

jim256

My own experience in the first 2000 miles has been better mileage when I stay in town, a little lower if I take a trip. I just made a 300 mile round trip, few stops, nearly all driving about 60 mph, 29 mpg.(All reference here are to average MPG, set at each tank refill). The prior tank, I never left town, 30.7 mpg. If you review the Lexus site for how the hybrid works and pay close attention to the display to see what is powering, when, I think you will increase your mileage. I find I don't need hills (there are few) to recharge the battery, just normal coasting and braking even in town. The more I am on battery, the better. In fact, if I buy gas at the station nearest home, drive straight home on the 2.5 mile trip through the residential streets, that trip will achieve 58-60 average mpg, nearly all on battery with a light foot and speeds of 25 or 35 mph. However, next trip with the engine on briefly at startup and also to recharge the battery as a result of the inbound trip, the average will drop to 30-31. That's only a total of 5 miles, but it is repeatable. I keep up with traffic, but do pay attention to the meter whenever possible and drive to achieve good mileage. If you work at it like I do, I think you'll see a consistent mileage, but local conditions and your driving style will be the biggest influence. I'm retired, so I don't need to hurry much.

Lil4X

For several months I've tried to limit the use of my cruise control on hilly (or freeway) terrain. Mine is an RX 330 and I haven't heard of a hybrid driver trying this, but it might be useful. Your cruise control works hard to maintain a pre-selected speed, opening the throttle perhaps a little quickly when the car slows a tiny bit - say, going up a slight incline. By anticipating hills a bit and trying to keep the throttle opening constant, or at least very gentle in application, I've found a 2 mpg (trip computer) improvement in mileage. Yes, you will have to accept slowing a few mph on uphill sections, but if you allow a little overspeed on the downhill, you can scrub it off on the next upgrade. You have to use a little judgment here, but it's worth a bit at the pump.

How this might apply to a hybrid, I can't say, but logic would seem to indicate it could be useful to try . . .

DennisL

"the battery will be charged by the engine which means using more fuel. "

I have also noticed my RX400h doing this, and it bugs me. I have two Prius', a 1st generation 2002 and a 2nd generation 2005, and neither of them have ever needed the engine to charge the hybrid battery (except on hot summer days with lots of air conditioning). And it seems the Prius' batteries stay rather charged all the time just with normal driving. Yet my RX400h needs to run the engine to charge the battery ??? and

Does this make sense? Or am I really in the Twilight Zone?

Dennis

jim256

I have not had a Prius, but mine will call on the ICE to recharge after extended low speed battery-only driving, and to provide constant power to the wheels when speeds are 40+ mph with some battery supplement. I expect the weight and performance of the RX will cause the differences you see. I still average 30 mph around town, 27-29 on trips. Unless you coast or brake a good bit, the ICE has to recharge the battery, there's no alternative and these are heavy cars. Are the meters designed to show the same info on the Prius as the RX?

Nextourer

No idea. It's possible that the RX is designed to use the battery to assist? I test drove the RX400h in May 2005 and I don't recall the battery losing a bar. It's possible that Toyota loosened the constraint compared to the Prius in terms of battery SOC management.

DennisL

Are the meters designed to show the same info on the Prius as the RX?

Yes. Same battery with horizontal bars. I think it might be the weight. I don't have the exact numbers at hand, but it seems like the Prius' weigh about half of the RX400h. I think you're right that it's weight and performance. A long slight downhill run in all of them will allow the car to just run on electric, but I can see how the Lexus system must be working much harder to keep all that mass going.

Dennis